Nonnative Wisterias (Wisteria spp.)
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Miller, J.H., E.B, Chambliss, N.J. Loewenstein. 2010. A Field Guide for the Identification of Invasive Plants in Southern Forests. General Technical Report SRS-119. Asheville, NC. United States Department of Agriculture, Forest Service. 126 p.
Contents |
Plant
Deciduous high climbing, twining, or trailing leguminous woody vines (or cultured as shrubs) to 70 feet (20 m) long. Chinese and Japanese wisteria difficult to distinguish due to hybridization.
Stem
Woody vines to 10 inches (25 cm) in diameter with infrequent alternate branching. Twigs densely short hairy. Older bark of Chinese wisteria tight and dark gray with light dots (lenticels) compared to white bark of Japanese wisteria.
Leaves
Alternate, odd-pinnately compound 4 to 16 inches (10 to 40 cm) long, with 7 to 13 leaflets (Chinese) or 13 to 19 leaflets (Japanese), and stalks with swollen bases. Leaflets oval to elliptic with tapering pointed tips, 1.6 to 3 inches (4 to 8 cm) long and 1 to 1.4 inches (2.5 to 3.5 cm) wide. Hairless to short hairy at maturity but densely silky hairy when young. Margins entire and wavy. Sessile or short petioled.
Flowers
March to May. Dangling and showy, stalked clusters (racemes) appearing when leaves emerge, 4 to 20 inches (10 to 50 cm) long and 3 to 3.5 inches (7 to 9 cm) wide. All blooming at about the same time (Chinese) or gradually from base (Japanese). Pealike flowers, corolla lavender to violet (to pink to white). Fragrant.
Fruit and seeds
July to November. Flattened legume pod, irregularly oblong to oblanceolate, 2.5 to 6 inches (6 to 15 cm) long and 0.8 to 1.2 inches (2 to 3 cm) wide. Velvety hairy, greenish brown to golden, splitting on 2 sides to release 1 to 8 flat, round, brown seeds, each 0.5 to 1 inch (1.2 to 2.5 cm) in diameter.
Ecology
Form dense infestations where previously planted. Occur on wet to dry sites. Colonize by vines twining and covering shrubs and trees and by runners rooting at nodes when vines covered by leaf litter. Seeds water-dispersed along riparian areas. Large seed size a deterrent to animal dispersal.
Resembles
Resembles native or naturalized American wisteria [W. frutescens (L.) Poir.], which occurs in wet forests and edges and sometimes forms large entanglements, flowers in June to August after leaves develop, and has 6-inch (15-cm) flower clusters, 9 to 15 leaflets, thin hairless, papery pods, and slender old vines. Also may resemble trumpet creeper [Campsis radicans (L.) Seem. ex Bureau], which has leaflets with coarsely toothed margins and white-hairy prominent veins beneath.
History and use
Introduced from Asia in the early 1800s. Traditional southern porch vines and still planted by mistaken gardeners.
Distribution
Found throughout the region with scattered dense infestations in every State. Especially frequent in SC and southwest AL.
Management strategies
- Do not plant. Remove prior plantings, and control sprouts and seedlings. Bag and dispose of plants and fruit in a dumpster or burn.
- Treat when new plants are young to prevent seed formation.
- Pull, cut, and treat when pods are not present.
- Anticipate wider occupation when plants are present before disturbance.
- Manually pull new seedlings when soil is moist, ensuring removal of all roots.
- Prescribed burning in spring can clear debris, sever climbing vines, and reveal hazards before summer applications.
- Repeated burning will not control.
Recommended control procedures
- Thoroughly wet all leaves (until runoff) with one of the following herbicides in water with a surfactant: (July to October for successive years when regrowth appears) Tordon 101* ‡ as a 3-percent solution (12 ounces per 3-gallon mix) or Tordon K* ‡ as a 2-percent solution (8 ounces per 3-gallon mix), or when soil activity is not desired: Garlon 4 as a 4-percent solution (1 pint per 3-gallon mix); (July to September for successive years when regrowth appears); Transline* † as a 0.5-percent solution in water (2 ounces per 3-gallon mix); or (September to October with repeated applications) a glyphosate herbicide as a 4-percent solution (1 pint per 3-gallon mix).
- For large vines, make stem injections using Arsenal AC*, Garlon 3A, or a glyphosate herbicide using dilutions and cutspacings specified on the herbicide label (anytime except March and April). The EZ-Ject tree injector assists in reaching through entanglements to treat. Spray the length of large surface vines using Garlon 4 as a 20-percent solution in a labeled basal oil product, vegetable oil, kerosene, or diesel fuel (where permitted) (5 pints per 3-gallon mix); or apply undiluted Pathfinder II to large vines, avoiding the bark of desirable trees.
* Nontarget plants may be killed or injured by root uptake.
‡ When using Tordon herbicides, rainfall must occur within 6 days after application for needed soil activation. Tordon herbicides are restricted use pesticides.
† Transline controls a narrow spectrum of plant species.
Images
 Photo by James H. Miller & Ted Bodner, Southern Weed Science Society, Bugwood.org September |  Photo by James H. Miller, USDA Forest Service, Bugwood.org May |  Photo by James H. Miller, USDA Forest Service, Bugwood.org May |  Photo by James H. Miller & Ted Bodner, Southern Weed Science Society, Bugwood.org March |
 Photo by James H. Miller & Ted Bodner, Southern Weed Science Society, Bugwood.org American Wisteria: July |
